1. Field of the Invention
The present invention relates to a vibrating gyro and a method of manufacturing the vibrating gyro, and more particularly, to a vibrating gyro, for example, used to prevent camera shake, or used in a car-navigation system, a pointing device and the like, and a method of manufacturing the vibrating gyro.
2. Description of the Related Art
FIG. 14 is a perspective view showing an example of conventional vibrating gyros. A vibrating gyro 1 includes a vibrator 2 which is formed by bonding a first piezoelectric substrate 3 and a second piezoelectric substrate 4. The first and second piezoelectric substrates 3 and 4 are bonded by a resin layer 5 made of, for example, epoxy resin, and polarized in opposite thickness directions as shown by the arrows.
A split electrode 6 is formed on the main outer surface of the first piezoelectric substrate 3. The electrode 6 is split in two in the widthwise direction of the first piezoelectric substrate 3 by a groove extending in the lengthwise direction, and furthermore, split in three in the lengthwise direction by two grooves extending in the widthwise direction near nodes of the vibrator 2. In other words, the electrode 6 is split into six. Furthermore, another electrode 7 is formed all over the main outer surface of the second piezoelectric substrate 4. Support members 8, which are formed of, for example, metal wires, are attached to the electrode 7 near the nodes of the vibrator 2 by solder, conductive paste or the like.
In this vibrating gyro 1, a drive signal is applied between two electrode portions 6a and 6b, which are located in the middle of the electrode 6 in the lengthwise direction, and the electrode 7 opposed thereto. Since the first and second piezoelectric substrates 3 and 4 are polarized in opposite directions, the vibrator 2 has a bimorph structure, and flexurally vibrates in the direction orthogonal to planes, where the electrodes 6 and 7 are formed, in response to the drive signal. At this time, the vibrator 2 flexurally vibrates about two nodes located a little inward from both ends in the lengthwise direction thereof. The identical signals are output from the electrode portions 6a and 6b at this time. The two signals are balanced and canceled to 0.
When the vibrator 2 rotates about the axis, a Coriolis force acts in the direction orthogonal to the flexural vibration of the vibrator 2. The direction of the flexural vibration of the vibrator 2 is changed thereby and output signals from the electrode portions 6a and 6b are also changed. In other words, when the output signal from one electrode portion 6a increases corresponding to the Coriolis force, the output signal from the other electrode portion 6b decreases corresponding to the Coriolis force. Therefore, only signals corresponding to the Coriolis force can be obtained by finding the difference between the output signals from these electrode portions 6a and 6b. Thus, the rotational angular velocity applied to the vibrating gyro 1 can be detected by measuring the difference between output signals from the electrode portions 6a and 6b.
However, epoxy resin used to join two piezoelectric substrates has a glass transition point. Above 80.degree. C., epoxy resin starts to soften, the quality factor Q declines, and sensitivity of the vibrating gyro also declines. If a material having a high Curie point such as LiNbO.sub.3 and LiTaO.sub.3 is used as the material of the piezoelectric substrates, deterioration of the temperature characteristic at high temperature impairs high heat resistance of the material as an advantage. Although the quality factors Q of these materials are high, the quality factor Q of epoxy resin is low, which lowers the quality factor Q of the whole vibrator. Furthermore, since real nodes of the vibrator are positioned on the center axis thereof, if a support member is attached to the surface of the vibrator, leakage of vibration from the support member is inevitable. In addition, if the support member is attached to the electrode on the surface of the vibrator, support strength thereof cannot be made higher than the adhesive strength between the electrode and the piezoelectric substrate, whereby the support member is likely to fall out due to a shock, such as a dropping of the vibrator.